1. Field of the Invention
The present invention relates to a developing cartridge installed in an electrophotographic image forming apparatus.
2. Description of the Related Art
In general, an electrophotographic image forming apparatus forms an image by scanning light onto a charged photosensitive medium to form an electrostatic latent image corresponding to a desired image. The electrostatic latent image is developed by supplying a toner onto the image. The developed image on the photosensitive medium is transferred through an intermediate transfer medium or directly onto a sheet of paper. The transferred image is fused using heat and pressure.
In the electrophotographic image forming apparatus, the photosensitive drum is generally provided as a cartridge since it is a consumable that should be replaced when its life span is completed. At least a part of the photosensitive drum is exposed to the outside of the cartridge to transfer the toner image developed on an outer circumference thereof onto the intermediate transfer medium or the paper. When the cartridge is separated from the image forming apparatus, light is irradiated onto the exposed portion, thereby degrading characteristics of the photosensitive medium. Therefore, the cartridge includes a protective cover for protecting the exposed portion of the photosensitive medium from natural light.
Japanese Laid-open Patent Publication JP 06-148965 discloses a developing cartridge having a protective cover for protecting a photosensitive drum. The protective cover is discharged out of the image forming apparatus by a paper conveying device when the developing cartridge is installed in the image forming apparatus. Thus, the developing cartridge is removed from the image forming apparatus, the photosensitive drum is exposed to natural light.
Japanese Laid-open Patent Publication JP. 06-186793, JP. 57-211181, and U.S. Pat. No. 5,113,220 disclose protective covers that are rotatably installed on developing cartridges. The protective cover is moved to a position for exposing the photosensitive drum from a position for protecting the photosensitive drum when the developing cartridge is installed in the image forming apparatus. However, the movement path of the protective cover or the position of the protective cover after moving operation exceeds the portion occupied by the developing cartridge. Therefore, other elements of the image forming apparatus cannot be arranged on the moving path of the protective cover and the portion occupied by the protective cover.